This invention relates to fibrous non-woven thermal insulating mats constructed of thermo-plastic fibers and particularly, though not exclusively, to high loft batts of linear condensation polymers, preferably polyester, for example, polyethylene teraphthalate (PET).
In the past, the production of polyester (e.g. PET) non-woven insulating mats constructed by melt-blowing techniques and R values of 4.0 or more per inch with mats using substantially continuous fibers of 3-12 microns have been suggested as possible. However, the production of high-loft batts suitable for the insulation of building structures have not proved easy to manufacture and mass production of such batts has not been achieved in spite of the research time and money devoted to producing such environmentally friendly products.
Low performance fibrous insulating materials have existed for decades, albeit exclusively for non durable goods. These uses continue to be the largest application for recycled PET and are commonly called FIBERFILL. In the 1960's 3M and others studied replacing fiber glass with plastic fibers but failed to develop high enough R-Values/inch to succeed commercially.
Meanwhile, the trend to conserve energy has increased standards for thermal performance. This has combined with rapidly escalating prices for lumber, other building components and labor costs to significantly increase demand for insulation with thermal resistance above R 4.0/inch.
Prototype prior art PET non-woven high loft batts have been quite thin (typically 1/8 inch thick and rarely over 1/2 inch thick). The problem of achieving high-loft batts having appropriate structural integrity has been the subject of much discussion in the prior art without a satisfactory solution being found. The prior art suggests that high-loft non-woven polyester batts may be produced, for example, by the use of bonding agents, adhesives, thermo-bonding fibers together, lamination, crimping fibers before batt formation, mixing thin fibers (required for good thermal insulation) with thicker fibers to provide structural integrity and resilience. None of the prior art proposals have been established as practical in a production environment capable of producing high-loft insulating batt at an acceptable cost.
The problems that have, until the present invention, defeated research and development are due to the incompatibility of the thin fibers, necessary for the desired insulation values, with the structural integrity, resilience, loft, compressive, tensile and burst strength etc. required of a practical high-loft insulation batt, plus the fibers have the tendency to form purely laminar structures, with no Z-direction orientation, that are not useful as batt insulation.
In addition, the prior art has only addressed the formation of simple polyester mats and has not addressed the formation of integral skins, special shapes, structural boards etc. from such materials.